Influence of fluoroquinolone consumption in inpatients and outpatients on ciprofloxacin-resistant Escherichia coli in a university hospital.

BACKGROUND: The increase in fluoroquinolone-resistant Escherichia coli has raised the issue of treatment failure in common infections. Few studies have investigated the possible relationship between outpatient fluoroquinolone consumption and resistance in hospital.
OBJECTIVE: To investigate the relationship between inpatient and outpatient fluoroquinolone use and ciprofloxacin-resistant E. coli in a teaching hospital.
METHODS: An ecological study was conducted in Toulouse University Hospital and its surrounding area, the Midi-Pyrénées region (south-western France), in 2004-07. Dynamic regression models were built to study how the hospital resistance rate was linearly related to current and past values of fluoroquinolone consumption. Resistance forecasts for 2008 were then calculated and compared with actual rates for the first 5 months of the year.
RESULTS: Mean resistance rate was 13.7% and mean fluoroquinolone use was 89.9 defined daily doses (DDDs)/1000 inpatient days in hospital and 2.6 DDDs/1000 inhabitants/day in the region. Taking into account past values of fluoroquinolone consumption in hospital and in outpatients, only levofloxacin use in the community remained significantly associated with resistance in hospital, with a lag of 12 months. This model explained 50% of the resistance variability.
CONCLUSIONS: This ecological analysis, conducted on a teaching hospital scale, suggests that ciprofloxacin resistance in E. coli in hospital is linked to consumption of fluoroquinolones within the hospital and its surrounding community. Among all fluoroquinolones, levofloxacin use was found to be the most important factor. Consumption in outpatients appears to be a relevant determinant to consider in designing interventions to reduce resistance in hospitals.